/*  ErroneousNumbers.swift  (c)  Kari Laitinen

    http://www.naturalprogramming.com

    2018-01-02  File created.

    This program shows how to throw and catch Errors in Swift.
*/

import Foundation

enum NumberError : Error
{
   case too_small
   case too_large
   case not_given
}

func get_number_from_keyboard()  throws  -> Int
{
   let optional_from_keyboard  =  Int( readLine()! )

   guard optional_from_keyboard != nil else
   {
      throw NumberError.not_given
   }

   // Now we can be sure that a valid number was given.
   // Let's store the optional value to a normal variable
   // and throw some errors if necessary.

   let number_from_keyboard = optional_from_keyboard!

   guard number_from_keyboard  >  99 else
   {
      throw NumberError.too_small
   }

   guard number_from_keyboard  <  999 else
   {
      throw NumberError.too_large
   }

   return number_from_keyboard
}

func get_number()  throws  -> Int
{
   var number_from_above_function  =  1234

   do
   {
      number_from_above_function  =  try get_number_from_keyboard()
   }
   catch NumberError.too_small
   {
      print( "\n NumberError.too_small caught. \n" )
   }

   return  number_from_above_function
}

// The main program begins.

print( "\n Please, type in a number: ", terminator: "" )

do
{
   let number_read_via_several_functions = try get_number()

   print( "\n The number from keyboard is : \( number_read_via_several_functions )\n" )
}
catch NumberError.too_large
{
   print( "\n NumberError.too_large caught. \n" ) 
}
catch
{
   // This block will catch NumberError.not_given

   print( "\n Some Error was caught. \n" )
}